<div mdl-shadow="2">
  <header>
    <button *ngIf="back" mdl-button="" mdl-button-type="icon" ng-reflect-mdl-button-type="icon" (click)="backClicked()" class="mdl-button mdl-button--icon iconfont icon-fanhui"></button> 
    <div>{{title}}</div>
  </header>
</div>